The present invention pertains to light control films that allow higher transmission over one range of viewing angles and lower transmission over another range of viewing angles and having an indicia that is visible only over a range of viewing angles.
Light control film (LCF), also known as light collimating film, is an optical film that is configured to regulate the transmission of light. Various LCFs are known, and typically include a light transmissive film having a plurality of parallel grooves wherein the grooves are formed of a light-absorbing material.
LCFs can be placed proximate a display surface, image surface, or other surface to be viewed. At normal incidence, (i.e. 0 degree viewing angle) where a viewer is looking at an image through the LCF in a direction that is perpendicular to the film surface, the image is viewable. As the viewing angle increases, the amount of light transmitted through the LCF decreases until a viewing cutoff angle is reached where substantially all the light is blocked by the light-absorbing material and the image is no longer viewable. This can provide privacy to a viewer by blocking observation by others that are outside a typical range of viewing angles.
LCFs can be prepared by molding and ultraviolet curing a polymerizable resin on a polycarbonate substrate. Such LCFs are commercially available from 3M Company, St. Paul, Minn., under the trade designation “3M™ Filters for Notebook Computers and LCD Monitors”.